Very Large Telescope observations of Gomez’s Hamburger: Insights into a young protoplanet candidate^⋆,⋆⋆

¹ Université de Toulouse, UPS-OMP, IRAP, 31028 Toulouse, France
² CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
³ Observatorio Astronómico Nacional, Apdo. 112, 28803 Alcalá de Henares, Madrid, Spain
⁴ Service d’Astrophysique CEA Saclay, France
⁵ Institut d’Astrophysique Spatiale, Paris-Sud 11, 91405 Orsay, France
⁶ Millenium Nucleus “Protoplanetary Disks in ALMA Early Science”, Universidad de Chile, Casilla 36-D, Santiago, Chile
⁷ UMI-FCA 3386, CNRS/INSU, Casilla 36-D, Santiago, Chile
⁸ Univ. Grenoble Alpes, IPAG, 38000 Grenoble, France, and CNRS, IPAG, 38000 Grenoble, France
⁹ Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Sor Juana Ines de la Cruz 3, 28049 Cantoblanco, Madrid, Spain
¹⁰ Centro de Astrobiología, CSIC-INTA, Ctra. de Torrejón a Ajalvir km 4, 28850 Madrid, Spain
¹¹ Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands

Received: 6 March 2015
Accepted: 19 May 2015

Abstract

Planets are thought to form in the gas and dust disks around young stars. In particular, it has been proposed that giant planets can form through the gravitational instability of massive extended disks around intermediate-mass stars. However, we still lack direct observations to constrain this mechanism. We have spatially resolved the 8.6 and 11.2 μm emission of a massive protoplanetary disk seen edge on around an A star, Gomez’s Hamburger (GoHam), using VISIR at the Very Large Telescope. A compact region situated at a projected distance of 350 ± 50 AU south of the central star is found to have a reduced emission. This asymmetry is fully consistent with the presence of a cold density structure, or clump, identified in earlier CO observations, and we derive physical characteristics consistent with those observations: a mass of 0.8−11.4 Jupiter masses (for a dust-to-gas mass ratio of 0.01), a radius of about 10² astronomical units, and a local density of about 10⁷ cm^-3. Based on this evidence, we argue that this clump, which we call GoHam b, is a promising candidate for a young protoplanet formed by gravitational instability that might be representative of the precursors of massive planets observed around A stars, such as HR 8799 or Beta pictoris. More detailed studies at high angular resolution are needed to better constrain the physical properties of this object to confirm this proposal.